Motor fuel



Patented Sept. e, was

PATENT OFFICE MOTOR FUEL Arthur L. Blount, Palos Verdes Estates, andBarold G. Reiber, Long Beach, (Jalii'.I asslgnors to Union Oil Companyof California, Los Angeles, Calif., a corporation of California NoDrawing.

Application September 27, 1985,

Serial N0. 42,510

18 Claims.

The present invention relates to a process and means for improving lowboiling hydrocarbon fractions, especially hydrocarbon-containing motorfuels such as gasoline, kerosene, motor benzol, or the like.

It is common knowledge that liquid hydrocarbon fuels produced on acommercial scale, and particularly those obtained from various crudepetroleurn oils by any of the well known processes of distillation,cracking or solvent extraction, contain gum or gum-forming constituentswhich are objectionable in many respects. Thesame may be said aboutmotor benzol which is a hydrocarbon fuel derived from coal-tar and whichcontains a large percentage of aromatic and unsaturated hydrocarbons.Gum or gum-forming tendencies of naphtha. gasolines, and similarlowboiling hydrocarbon fractions is determined by the method No. 530.1in the United States Bureau of Mines Technical Paper 3233, page 96.entitled "Specification for Petroleum Products and Methods of Testing",revised October 21, 1927. In brief. this method consists in placing 100c. c. of the liquid hydrocarbon to be tested in a spun copper dish aboutthree and one-half inches in diameter on a steam bath, and evaporatingoil the volatile material. The result is expressed as milligrams of gumleft in the dish per 100 c. c. of gasoline, naphtha or similar lowboiling fractions.

The presence of gum-forming constituents is especially pronounced in thecase of gasoline produced by any of the well known cracking processes.Although such gasolines constitute excellent motor fuels from ananti-knock standpoint, they are objectionable in view of the fact thatthey contain or develop large amounts of gum on storage, and /or tend todeposit gum in various parts of an internal combustion engine, thusinterfering with its eiijcient operation. They are likewise quiteunstable with respect to color and darken even on standing for a fewdays.

It has been customary to chemically refine gasolines, naphthas and otherhydrocarbon-containing motor fuels to remove the highly unsaturatedcompounds present therein which are responsible for the above mentionedgum formation. Although by such treatment an improved motor fuel may beobtained from the standpoint of gum formation and/or deposition, theantiknock value thereof is generally considerably impaired because suchchemical treatments not only remove the highly unsaturated bodies deemedresponsible for the production of gums but also remove hydrocarbons of alesser degree of unsaturated and aromatic compounds which con- 'stitutethe desirable anti-knock constituents of the motor fuel.

The presence of unsaturated hydrocarbons even those of the typeresponsible for the formation of gums or gummy products is notundesirable and would even be beneficial were it not for the fact thatin the presence of air or oxygen during storage or use, they tend toabsorb oxygen with the formation of the above mentioned undesirableproducts, thereby impairing the value and usefulness of the motor fuel.

On account of this, a producer of hydrocarboncontalning motor fuelswhich contain unsaturated compounds is continuously confronted with theproblem of gum formation.

Hence, it is an object of our invention to produce high grade motorfuels having no or a substantially reduced gum-forming tendency andwhich do not exhibit any tendency to become discolored on standing.

It is another object of our invention to present a series of compoundswhich, when added to hydrocarbon-containing motor fuels which normallytend to form gums during the usual conditions of storage, inhibit orsubstantially reduce such gum-forming tendencies, and render them morestable with respect to color.

Other objects will be apparent from the description of our inventiongiven hereinafter.

According to our invention, the usual chemical purification processeswhich, as previously stated, tend to remove certain desirable fractionsfrom various motor fuels, may be substantially reduced in intensity ormay even be entirely eliminated Without danger of presenting an inferiorquality motor fuel. By adding suitable amounts of the compoundsdescribed below, to a motor fuel, it is possible to obtain onecontaining all the desirable components including unsaturatedhydrocarbons without having to consider the possibility of gum formationtherein during the usual periods or conditions of storage or use.

We have discovered that certain organic compounds containing arsenic, ifadded to any of the motor fuels set forth above, inhibit the formationof gum or reduce the quantity thereof as determined by the previouslydescribed copper dish test or by any other test commonly employed fordetecting gums. Their presence in a motor fuel will also tend tostabilize the color thereof as explained hereinafter.

The organic compounds of arsenic, which we have found to constituteexcellent inhibitors or retarders for gum formation inhydrocarbon-containing motor fuels which, in the absence of thesecompounds, tend to form substantial amounts of gum, are compounds of thetype:

As-R aryl or alkoxy-aryl arsine with an aliphatic aldehyde. Specificcompounds falling within the above identified class are: tetrahydro-Zi,6-dimethyl-2, 5-diphenyl-1, 4, 2, 5-dioxdiarsine,

o--on'cn.

HaC- C-O tetrahydro-li, 0-dimethyl-2, 5-ditolyl-1, 4, 2, 5-dioxdiarsine.

o--ca-om cal-cams summons tetrahydro-3, 8 dimethyl 2, 5 di p-ethoxyphenyl-l, 4, 2, 5-diozdiarsine,

o-oa-om CJHIOOM AsCsHcOCsHs.

Likewise, suitable amounts of mixtures of any or all of the abovementioned compounds or mixtures of these and compounds of the same classbut containing different aryl or alkoxy-aryl substituents may be addedto the motor fuel to decrease or inhibit gum formation therein and toprevent them from becoming discolored on standing.

Other compounds which we have found to substantially retard or inhibitthe formation of gums in hydrocarbon-containing motor fuels are thoseobtained by condensing an aromatic aldehyde with a primary arsine. Thesecompounds have the general formula: R-As-(CHOHR): wherein R is an arylor alkoxy-aryl group. Compounds falling within this group and whichexcellent gum inhibiting tendencies are: bism-hydroxybenzyl)phenylarsine CsHsA8(CHOHCsHs) a; bis(-s-hydromolyl) tolylarsineHsCCeHiAS (CHOHCeHsCHa) s and his a -hydroxybenzyl) ptolyl arsineCHsCsHe-As-(CHOHCsHs) I.

Mixtures of any or all of the above as well as mixtures of any or all ofthese and one or more of the compounds of the type o-onm BAs As1lhydrocarbon fuels into which they are introduced and will continue theirstabilizing action for days and even months. Their presence in ahydrocarbon-containing fuel will prevent the absorption of oxygen bycertain of the more unsaturated compounds present which absorption ifnot inhibited results in the formation of gums or gummy products. Thisgum formation is a cataiytic process 1. e. the rate of the formation ofgums is catalyzed by those gums already present.

The quantity of the material added to the motor fuels for inhibiting theformation of gums may be very small. In general, amounts of theinhibitor varying from 0.001% to 0.1% by weight with respect to thehydrocarbon-containing motor fuel to which they are added. areinsuflicient to inhibit or substantially retard any gum-forming tendencytherein, although in some instances greater or smaller amounts may beadded.

The method of adding our inhibitors is exceedingly simple. For example,we may dissolve a quantity of the inhibitor in a small portion of theparticular fuel to which it is to be added to form a concentratedsolution thereof and then add a sumcient amount of this solution to thefuel to be treated. Or, a suitable amount may be directly added to alarge volume of the fuel and dissolved therein by proper agitation. Insome instances it may be preferable to dissolve the inhibitor in ahydrocarbon-cobble solvent such as bensoi, absolute alcohol or ether,and add suitable amounts of this solution to the motor fuel.

The following examples are illustrative of our invention: A pressuredistillate having a gravity of 522 A. P. I. and which had been givenonly a mild acid treatment (2% lbs. of H280. per barrel) followed byredistiilation, was found to have a copper dish gum test of 70 mgs. per100 c. c. without addition of any inhibitor. Upon addition of 0.005% oftetrahydro-3,8-dimethyl-15-diphenyl- 1,43,5-dioxdiarsine, the gumcontent decreased to 21 mgs. per 100 c. c.

A second pressure distillate with a gravity of 44.7 A. P. I. and whichhad been subiected to a treatment with sodium plunibite had an initialcopper dish gum test of 872 mgs. per 100 c. c. When 0.01% oftetrahydro-md-dimethyl-zb-diphenyl-1,4.2,5-dioxdiarsine was added to 100c. c. of this distillate, its gum content amounted to only 88 mgs. Whenthis same pressure distillate (100 c. c.) was treated with 0.01% of agum inhibitor sold under the trade name Vanoline (parahydroxy diphenylamine) its gum content was reduced to only 616 mgs. per 0. c.

The formation of gums in hydrocarbon-containing motor fuels on storageis closely associated with an increase in color intensity of theparticular fuel. Our inhibitors are found not only to exert aninhibiting tendency toward gum formation even on storage over prolongedperiods of time but also are responsible for the prevention ofundesirable color formation. The term "inhibiting gum formation" used inthe present specification and claims is meant to include the feature ofcolor stabilization. The following example is illustrative of thisfeature of our invention:

A pressure distillate which had been given a slight acid treatment (2%lbs. of 11,504 per barrel) and which had been subsequently redistilledand doctor treated had an initial color of 1 N. P. A. which afterstorage of the distillate for a period of 14 days increased to 1% N. P.A. When adding 0.005% of tetrahydro-3,6-dimethyl-2,5-dipheml-L42j-dioxdiarsine to a fresh c. 0. sample thereof, the colorwas still better than 1% N. P. A. after standing over a period of 4months.

As previously stated, the usual chemical refining of the motor fuel,consisting of a treatment with concentrated sulfuric acid, alkalitreatin the acid treated fuel and subsequently water washing may besubstantially reduced in intensity or even entirely omitted. However. weprefer to subject the hydrocarbon-containing motor fuel to a treatmentwith sodium plumbite or an equivalent agent (to remove injurious sulfurcompounds) prior to adding our inhibitors.

Although the compounds set forth herein are especially suitable forstabilizing cracked gasolines or blends of cracked and straight rungasolines with respect to the formation of gum, they may be equally welladded to other hydrocarboncontaining motor fuels which containgumforming constituents. They likewise will act as antioxidants inheavier petroleum fractions such as kerosene, gas oil, lubricating oiland the like.

Gum tests are generally conducted by the previously mentioned copperdish method, but sometimes by a similar test in which a porcelain dishis used. However, by either method of test, our process is found toreduce or inhibit gum formation.

The term N. P. A. color" used herein relates to a color grade of aliquid obtained by means of the Union Petroleum colorimeter adapted as astandard of the National Petroleum Association in 1915. A detaileddescription of the apparatus, method of test and significance of scalereadings may be found in David T. Day--Handbook of Petroleum Ind., 1922,vol. 1, page 665."

The examples and theories set forth herein are not to be considered aslimitations upon our process. As to the scope of our invention,reference is hereby made to the appended claims.

We claim:

1. In a process for inhibiting gum formation in hydrocarbon-containingmotor fuels which normally develop gum during the usual conditions ofstorage, the step of adding thereto small amounts of an organic arseniccompound of the type wherein R is an aryl or alkoxy-aryl group, and R isan alkyl group from the class consisting of methyl, ethyl and propylgroups.

2. In a process for inhibiting gum formation in hydrocarbon-containingmotor fuels which normally develop gum during the usual conditions-ofstorage, the step of adding thereto between 0.001 and 0.1% of an organicarsenic compound of the type wherein R is an aryl or alkoxy-aryl group,and R is a lower alkyl group.

3. In a process for inhibiting gum formation in hydrocarbon-containingmotor fuels which normally develop gum during the usual conditions ofstorage, the step of adding thereto small amounts oftetrahydro,-3,6-dialkyl-2,5-diphenyl- 1,4,2,5,-dioxdiaraine.

4. In a process for inhibiting gum formation in hydrocarbon-containingmotor fuels which normally develop gum during the usual conditions ofstorage, the step of adding thereto small amounts of tetrahydro, 3,6dialkyl 2,5 ditolyl,-1,4,2,5-dioxdiarsine.

5. In a process for inhibiting gum formation in hydrocarbon-containingmotor fuels which normally develop gum during usual conditions 01storage, the step of adding thereto a very small percentage of atetrahydro dialkyl diaryldioxdiarsine.

6. Hydrocarbon-containing motor fuels which normally develop gum duringthe usual conditions of storage and containing an organic arseniccompound of the type OCHR As-R wherein R is an aryl or alkoxy-aryl groupfrom the class consisting of phenyl, tolyl, oxyphenyl and oxytolylgroups, and R is a lower alkyl group.

'7. Motor fuels containing hydrocarbons which normally develop gumduring the usual conditions of storage and containing a small proportionof tetrahydro,-3,6 dialkyl 2,5 diphenyl 1,4,2,5,-dioxdiarsine.

8. Motor fuels containing hydrocarbons which normally develop gum duringthe usual conditions of storage and containing a small proportion oftetrahydro,-3,6-dia1kyl-2,5-di-tolyl,1,4,2,5-dioxdiarsine.

9. Motor fuels containing hydrocarbons which normally develop gum duringthe usual conditions of storage and containing between 0.001 and 0.1% oftetrahydro,3,6-dialkyl-2,5 diphenyl 1,42,5-

dioxdiarsine, the alkyl being taken from themethyl, ethyl and propyigroups.

10. Motor fuels containing hydrocarbons which normally develop gumduring the usual conditions of storage and containing between 0.001 and0.1% of tetrahydro,-3,6-dialkyl-2,5-di-tolyl,1,4,2,5-dioxdiarsine, thealkyl being taken from the methyl, ethyl and propyl groups.

11. Motor fuels comprising cracked gasoline containing small amounts ofan organic arsenic compound of the type 0cnn R-As s-R R c-o wherein R isan aryl or alkoxy-aryl group, and R a lower alkyl group.

12. Motor fuels comprising hydrocarbons which normally develop gumduring usual conditions of storage containing small quantities in theorder of 0.001% to 0.1% of a tetrahydro-dialkyl-diaryldioxdiarsine.

13. A process for inhibiting gum formation in hydrocarbon-containingmotor fuels which normally develop gum during the usual conditions ofstorage which comprise adding thereto small amounts of organic arseniccompounds of the type R-As-(CHOHR) 2 wherein R is an aryl, or alkoxyarylgroup.

14. A hydrocarbon-containing motor fuel which normally develops gumunder oxidizing conditions containing a small amount sufficient toinhibit such gum formation of an organic arsenic compound of the typeR-As (CHOHR): wherein R is an aryl or alkoxy-aryl group.

15. A composition as defined in claim 14 wherein the compound added isbis(-a-hydroxy benzyl) phenyl arsine CtHsAS(CHOHCsHs) 2.

16. Hydrocarbon-containing motor fuels which normally develop gum duringthe usual conditions 4- memos of storage, containing between 0.001% and0.1% wherein R is an aryl or aikoxy-aryl group and R or a compound ofthe class consisting oi. an orslower alkyl group, and an organic arseniccomganic arsenic compound of the type pound of the type R-A8(CHOHR)2wherein R is O OHBI an aryl group. R ARTHUR BLOUNT. 5

HAROLD REIBER.

CERTIFIOATEOF CORRECTION. Potent No. 2,129,195. 7 September 6, 1958.

i ARTHUR If. BLOUNI', ET AL.

It is'hereby certified thslt error appears in the printed specificationof the nbox re numberen patentrequiring correction as follows: Page 2,second colmnn, line 16, for "insufficient" read sufficient; and that thesaid Letters Patent shoulnbe rend. with this correction therein that thesame may confer-m te the record of the case in the Patent Office.

Signed and sealed this 27th day of ecember A. D. 1958.

Henry Van Airedale (Seal) iicting Gemnissioner of Patents.

4- memos of storage, containing between 0.001% and 0.1% wherein R is anaryl or aikoxy-aryl group and R or a compound of the class consistingoi. an orslower alkyl group, and an organic arsenic comganic arseniccompound of the type pound of the type R-A8(CHOHR)2 wherein R is O OHBIan aryl group. R ARTHUR BLOUNT. 5

HAROLD REIBER.

CERTIFIOATEOF CORRECTION. Potent No. 2,129,195. 7 September 6, 1958.

i ARTHUR If. BLOUNI', ET AL.

It is'hereby certified thslt error appears in the printed specificationof the nbox re numberen patentrequiring correction as follows: Page 2,second colmnn, line 16, for "insufficient" read sufficient; and that thesaid Letters Patent shoulnbe rend. with this correction therein that thesame may confer-m te the record of the case in the Patent Office.

Signed and sealed this 27th day of ecember A. D. 1958.

Henry Van Airedale (Seal) iicting Gemnissioner of Patents.

